Fungicidal compositions

ABSTRACT

The invention comprises a method of combating phytopathogenic diseases on crop plants which comprises applying to the crop plants or the locus thereof being infested with said phytopathogenic disease an effective amount of a combination of  
     a) a benzophenone of formula I  
                 
 
     wherein  
     R 1  is methoxy, methyl, hydroxy, acetoxy or pivaloyloxy,  
     R 2  is C 1 -C 4 alkoxy or 2-halogenbenzyloxy,  
     R 3  is C 1 -C 4 alkoxy,  
     R 4  is C 1 -C 4 alkyl, halogen or trifluoromethyl, and  
     R 5  is hydrogen, halogen, C 1 -C 4 alkoxy, trifluoromethyl or nitro;  
     in association with  
     b) the strobilurin of formula II  
                 
 
     and a composition comprising fungicidally effective amounts of components I and II. and a composition

[0001] The present invention relates to novel fungicidal compositionsfor the treatment of phytopathogenic diseases of crop plants, especiallyphytopathogenic fungi, and to a method of combating phytopathogenicdiseases on crop plants.

[0002] It is known that certain substituted benzophenone derivativeshave biological activity with high systemicity against phytopathogenicfungi, e.g. known from EP-A-897904, EP-A-899255 and EP-A-967196 wheretheir properties and methods of preparation are described. On the otherhand certain strobilurin derivatives, cyanoimidazole and carbonic acidamide compounds are known from the literature as plant fungicides forapplication in various crops of cultivated plants. However, croptolerance and activity against phytopathogenic plant fungi of the knowncompounds do not always satisfy the needs of agricultural practice inmany incidents and aspects.

[0003] It has now been found that the use of

[0004] a) a benzophenone of formula I

[0005] wherein

[0006] R₁ is methoxy, methyl, hydroxy, acetoxy or pivaloyloxy,

[0007] R₂ is C₁-C₄alkoxy or 2-halogenbenzyloxy,

[0008] R₃ is C₁-C₄alkoxy,

[0009] R₄ is C₁-C₄alkyl, halogen or trifluoromethyl, and

[0010] R₅ is hydrogen, halogen, C₁-C₄alkoxy, trifluoromethyl or nitro;

[0011] in association with

[0012] b) the strobilurin of formula II

[0013] is particularly effective in combating or preventing fungaldiseases of crop plants. These combinations exhibit synergisticfungicidal activity.

[0014] The compounds of formula I are known from EP-A-897904,EP-A-899255 and EP-A-967196. Specific examples of preferred individualcompounds are listed in the following table. No. R₁ R₂ R₃ R₄ R₅ 1.01OCH₃ OCH₃ OCH₃ CH₃ Br 1.02 OCH₃ OCH₃ OCH₃ CH₃ Cl 1.03 OCH₃ OC₂H₅ OCH₃CH₃ Cl 1.04 OCH₃ OC₃H₇-n OCH₃ CH₃ Cl 1.05 OCH₃ OCH₃ OCH₃ CH₃ CF₃ 1.06OCH₃ OCH₃ OCH₃ Cl H 1.07 OCH₃ OCH₃ OCH₃ CF₃ H 1.08 OCH₃ OCH₃ OCH₃ CH₃ H1.09 OCH₃ OCH₃ OCH₃ Cl Br 1.10 OCH₃ OCH₃ OCH₃ Cl CH₃ 1.11 CH₃ OCH₃ OCH₃CH₃ Cl 1.12 CH₃ OCH₃ OCH₃ CH₃ Br 1.13 CH₃ OCH₃ OCH₃ CH₃ NO₂ 1.14 CH₃OCH₃ OCH₃ CH₃ OCH₃ 1.15 CH₃ OCH₃ OC₄H₉-n CH₃ Cl 1.16 CH₃ OCH₃ OC₄H₉-nCH₃ Br 1.17 CH₃ OCH₃ OC₄H₉-n CH₃ NO₂ 1.18 CH₃ OCH₃ OC₄H₉-n CH₃ OCH₃ 1.19CH₃ —OCH₂-2- OC₄H₉-n CH₃ Cl F—C₆H₄ 1.20 CH₃ —OCH₂-2- OC₄H₉-n CH₃ BrF—C₆H₄ 1.21 CH₃ —OCH₂-2- OC₄H₉-n CH₃ NO₂ F—C₆H₄ 1.22 CH₃ —OCH₂-2-OC₄H₉-n CH₃ OCH₃ F—C₆H₄ 1.23 OH OCH₃ OCH₃ CH₃ H 1.24 CH₃—CO—O— OCH₃ OCH₃CH₃ H 1.25 OH OCH₃ OCH₃ CH₃ Br 1.26 CH₃—CO—O— OCH₃ OCH₃ CH₃ Br 1.27 OHOCH₃ OCH₃ CH₃ Cl 1.28 CH₃—CO—O— OCH₃ OCH₃ CH₃ Cl 1.29 (CH₃)₃C—CO—O— OCH₃OCH₃ CH₃ Br

[0015] The chemical designation of the above listed compounds is asfollows:

[0016] I.01 5-bromo-6,6′-dimethyl-2,2′,3′,4′-tetramethoxy-benzophenone,

[0017] I.02 5-chloro-6,6′-dimethyl-2,2′,3′,4′-tetramethoxy-benzophenone,

[0018] I.035-chloro-6,6′-dimethyl-3′-ethoxy-2,2′,4′-trimethoxy-benzophenone,

[0019] I.045-chloro-6,6′-dimethyl-3′-propoxy-2,2′,4′-trimethoxy-benzophenone,

[0020] I.055-trifluoromethyl-6,6′-dimethyl-2,2′,3′,4′-tetramethoxy-benzophenone,

[0021] I.06 6-chloro-6′-methyl-2,2′,3′,4′-tetramethoxy-benzophenone,

[0022] I.076-trifluoromethyl-6′-methyl-2,2′,3′,4′-tetramethoxy-benzophenone,

[0023] I.08 6,6′-dimethyl-2,2′,3′,4′-tetramethoxy-benzophenone,

[0024] I.095-bromo-6-chloro-6′-methyl-2,2′,3′,4′-tetramethoxy-benzophenone,

[0025] I.10 6-chloro-5,6′-dimethyl-2,2′,3′,4′-tetramethoxy-benzophenone,

[0026] I.11 5-chloro-2,6,6′-trimethyl-2′,3′,4′-trimethoxy-benzophenone,

[0027] I.12 5-bromo-2,6,6′-trimethyl-2′,3′,4′-trimethoxy-benzophenone,

[0028] I.13 5-nitro-2,6,6′-trimethyl-2′,3′,4′-trimethoxy-benzophenone,

[0029] I.14 2,6,6′-trimethyl-5,2′,3′,4′-tetramethoxy-benzophenone,

[0030] I.155-chloro-2,6,6′-trimethyl-2′-butoxy-3′,4′-dimethoxy-benzophenone,

[0031] I.165-bromo-2,6,6′-trimethyl-2′-butoxy-3′,4′-dimethoxy-benzophenone,

[0032] I.175-nitro-2,6,6′-trimethyl-2′-butoxy-3′,4′-dimethoxy-benzophenone,

[0033] I.18 2,6,6′-trimethyl-2′-butoxy-5,3′,4′-trimethoxy-benzophenone,

[0034] I.195-chloro-2,6,6′-trimethyl-2′-(o-fluorobenzyloxy)-3′,4′-dimethoxy-benzophenone,

[0035] I.205-bromo-2,6,6′-trimethyl-2′-(o-fluorobenzyloxy)-3′,4′-dimethoxy-benzophenone,

[0036] I.215-nitro-2,6,6′-trimethyl-2′-(o-fluorobenzyloxy)-3′,4′-dimethoxy-benzophenone,

[0037] I.222,6,6′-trimethyl-2′-(o-fluorobenzyloxy)-5,3′,4′-trimethoxy-benzophenone,

[0038] I.23 6,6′-dimethyl-2-hydroxy-2′,3′,4′-trimethoxy-benzophenone,

[0039] I.24 6,6′-dimethyl-2-acetoxy-2′,3′,4′-trimethoxy-benzophenone,

[0040] I.255-bromo-6,6′-dimethyl-2-hydroxy-2′,3′,4′-trimethoxy-benzophenone,

[0041] I.265-bromo-6,6′-dimethyl-2-acetoxy-2′,3′,4′-trimethoxy-benzophenone,

[0042] I.275-chloro-6,6′-dimethyl-2-hydroxy-2′,3′,4′-trimethoxy-benzophenone,

[0043] I.285-chloro-6,6′-dimethyl-2-acetoxy-2′,3′,4′-trimethoxy-benzophenone, and

[0044] I.295-bromo-6,6′-dimethyl-2-pivaloyloxy-2′,3′,4′-trimethoxy-benzophenone.

[0045] The compound of formula II is known from the literature undercommon name azoxystrobin, code ICIA5504, e.g. from EP-A-382375.

[0046] Among these mixtures those are preferred in which the compound offormula I is one of the compounds I.01, I.06, I.07, I.08, I.09, I.10,I.11, I.12, I.13, I.14, I, 25, I.26 or I.27.

[0047] Throughout this document the expression combination stands forthe various combinations of components a) and b), e.g. in a single“ready-mix” form, in a combined spray mixture composed from separateformulations of the single active ingredient components, e.g. a“tank-mix”, and in a combined use of the single active ingredients whenapplied in a sequential manner, i.e. one after the other with areasonably short period, e.g. a few hours or days. The order of applyingthe components a) and b) is not essential for working the presentinvention.

[0048] The combinations according to the invention may also comprisemore than one of the active components a), if broadening of the spectrumof disease control is desired. For instance, it may be advantageous inthe agricultural practice to combine two or three components a) with thecompound of formula II.

[0049] The active ingredient combinations are effective againstphytopathogenic fungi belonging to the following classes: Ascomycetes(e.g. Venturia, Podosphaera, Erysiphe, Monilinia, Mycosphaerella,Uncinula); Basidiomycetes (e.g. the genus Hemileia, Rhizoctonia,Puccinia); Fungi imperfecti (e.g. Botrytis, Helminthosporium,Rhynchosporium, Fusarium, Septoria, Cercospora, Alternaria, Pyriculariaand Pseudocercosporella herpotrichoides); Oomycetes (e.g. Phytophthora,Peronospora, Bremia, Pythium, Plasmopara).

[0050] Target crops for the areas of indication disclosed hereincomprise within the scope of this invention e.g. the following speciesof plants: cereals (wheat, barley, rye, oats, rice, sorghum and relatedcrops); beet (sugar beet and fodder beet); pomes, stone fruit and softfruit (apples, pears, plums, peaches, almonds, cherries, strawberries,raspberries and black-berries); leguminous plants (beans, lentils, peas,soybeans); oil plants (rape, mustard, poppy, olives, sunflowers,coconut, castor oil plants, cocoa beans, groundnuts); cucumber plants(marrows, cucumbers, melons); fibre plants (cotton, flax, hemp, jute);citrus fruit (oranges, lemons, grapefruit, mandarins); vegetables(spinach, lettuce, asparagus, cabbages, carrots, onions, tomatoes,potatoes, paprika); lauraceae (avocados, cinnamon, camphor); or plantssuch as maize, tobacco, nuts, coffee, sugar cane, tea, vines, hops,turf, bananas and natural rubber plants, as well as ornamentals(flowers, shrubs, broad-leaved trees and evergreens, such as conifers).This list does not represent any limitation.

[0051] The combinations of the present invention may also be used in thearea of protecting technical material against attack of fungi. Technicalareas include wood, paper, leather, constructions, cooling and heatingsystems, ventilation and air conditioning systems, and the like. Thecombinations according the present invention can prevent thedisadvantageous effects such as decay, discoloration or mold.

[0052] The combinations according to the present invention areparticularly effective against powdery mildews and rusts, pyrenophora,rhynchosporium, tapesia, fusarium and leptosphaeria fungi, in particularagainst pathogens of monocotyledonous plants such as cereals, includingwheat and barley. They are furthermore particularly effective againstdowny mildew species, powdery mildews, leaf spot diseases and rusts indicotyledonous plants.

[0053] The amount of combination of the invention to be applied, willdepend on various factors such as the compound employed, the subject ofthe treatment (plant, soil, seed), the type of treatment (e.g. spraying,dusting, seed dressing), the purpose of the treatment (prophylactic ortherapeutic), the type of fungi to be treated and the application time.

[0054] It has been found that the use of compounds of formula II incombination with the compound of formula I surprisingly andsubstantially enhance the effectiveness of the latter against fungi, andvice versa. Additionally, the method of the invention is effectiveagainst a wider spectrum of such fungi that can be combated with theactive ingredients of this method, when used solely.

[0055] The weight ratio of a):b) is so selected as to give a synergisticfungicidal action. In general the weight ratio of a):b) is between 200:1and 1:40. The synergistic action of the composition is apparent from thefact that the fungicidal action of the composition of a)+b) is greaterthan the sum of the fungicidal actions of a) and b).

[0056] The method of the invention comprises applying to the treatedplants or the locus thereof in admixture or separately, a fungicidallyeffective aggregate amount of a compound of formula I and a compound ofcomponent b).

[0057] The term locus as used herein is intended to embrace the fieldson which the treated crop plants are growing, or where the seeds ofcultivated plants are sown, or the place where the seed will be placedinto the soil. The term seed is intended to embrace plant propagatingmaterial such as cuttings, seedlings, seeds, germinated or soaked seeds.

[0058] The novel combinations are extremely effective on a broadspectrum of phytopathogenic fungi. Some of them have a systemic actionand can be used as foliar and soil fungicides and for seed dressing.

[0059] The fungicidal combinations are of particular interest forcontrolling a large number of fungi in various crops or their seeds,especially wheat, rye, barley, oats, rice, maize, lawns, cotton,soybeans, coffee, sugarcane, fruit and ornamentals in horticulture andviticulture, in vegetables such as cucumbers, beans and cucurbits, andin field crops such as potatoes, peanuts, tobacco and sugarbeets.

[0060] The combinations are applied by treating the fungi or the seeds,plants or materials threatened by fungus attack, or the soil with afungicidally effective amount of the active ingredients.

[0061] The agents may be applied before or after infection of thematerials, plants or seeds by the fungi.

[0062] The novel combinations are particularly useful for controllingthe following plant diseases:

[0063]Erysiphe graminis in cereals,

[0064]Erysiphe cichoracearum and Sphaerotheca fuliginea in cucurbits,

[0065]Podosphaera leucotricha in apples,

[0066]Uncinula necator in vines,

[0067] Puccinia species in cereals,

[0068] Rhizoctonia species in cotton, potatoes, rice and lawns,

[0069] Ustilago species in cereals and sugarcane,

[0070]Venturia inaequalis (scab) in apples,

[0071] Helminthosporium species in cereals,

[0072]Septoria nodorum in wheat,

[0073]Septoria tritici in wheat,

[0074]Rhynchosporium secalis on barley,

[0075]Botrytis cinerea (gray mold) in strawberries, tomatoes and grapes,

[0076]Cercospora arachidicola in groundnuts,

[0077]Peronospora tabacina in tobacco, or other Peronospora in variouscrops,

[0078]Pseudocercosporella herpotrichoides in wheat and barley,

[0079]Pyrenophera teres in barley,

[0080]Pyricularia oryzae in rice,

[0081]Phytophthora infestans in potatoes and tomatoes,

[0082] Fusarium and Verticillium species in various plants,

[0083]Plasmopara viticola in grapes,

[0084] Alternaria species in fruit and vegetables,

[0085]Pseudoperonospora cubensis in cucumbers,

[0086]Mycosphaerella fijiensis in banana,

[0087] Colleotrichum species in various crops.

[0088] When applied to the plants the compounds of formula I are appliedat a rate of 20 to 2000 g/ha, particularly 20 to 1000 g/ha, e.g. 20, 30,40, 75, 80, 100, 125, 150, 175, 200, 300, 500, 750, 1000, 1200, 1500 or2000 g/ha, in association with 10 to 750 g/ha, particularly 20 to 1000g/ha, e.g. 12.5 g/ha, 15 g/ha, 30 g/ha, 40 g/ha, 60 g/ha, 75 g/ha,80/ha, 100 g/ha, 125 g/ha, 150 g/ha, 175 g/ha, 200 g/ha, 250 g/ha, 300g/ha, 500 g/ha, 600 g/ha or 750 g/ha of the compound of formula II.

[0089] In agricultural practice the application rates of the combinationdepend on the type of effect desired, and range from 0.02 to 3 kg ofactive ingredient per hectare.

[0090] When the active ingredients are used for treating seed, rates of0.001 to 50 g a.i. per kg, and preferably from 0.01 to 10 g per kg ofseed are generally sufficient.

[0091] The invention also provides fungicidal compositions comprising acompound of formula I and the compound of formula II.

[0092] The composition of the invention may be employed in anyconventional form, for example in the form of a twin pack, an instantgranulate, a flowable formulation, an emulsion concentrate or a wettablepowder in combination with agriculturally acceptable adjuvants. Suchcompositions may be produced in conventional manner, e.g. by mixing theactive ingredients with appropriate adjuvants (diluents or solvents andoptionally other formulating ingredients such as surfactants). Alsoconventional slow release formulations may be employed where longlasting efficacy is intended.

[0093] Particularly formulations to be applied in spraying forms such aswater dispersible concentrates or wettable powders may containsurfactants such as wetting and dispersing agents, e.g. the condensationproduct of formaldehyde with naphthalene sulphonate, analkylarylsulphonate, a lignin sulphonate, a fatty alkyl sulphate, andethoxylated alkylphenol and an ethoxylated fatty alcohol.

[0094] A seed dressing formulation is applied in a manner known per seto the seeds employing the combination of the invention and a diluent insuitable seed dressing formulation form, e.g. as an aqueous suspensionor in a dry powder form having good adherence to the seeds. Such seeddressing formulations are known in the art. Seed dressing formulationsmay contain the single active ingredients or the combination of activeingredients in encapsulated form, e.g. as slow release capsules ormicrocapsules.

[0095] In general, the formulations include from 0.01 to 90% by weightof active agent, from 0 to 20% agriculturally acceptable surfactant and10 to 99.99% solid or liquid adjuvant(s), the active agent consisting ofat least a compound of formula I together with the compound of formulaII, and optionally other active agents, particularly microbides orconservatives or the like. Concentrated forms of compositions generallycontain in between about 2 and 80%, preferably between about 5 and 70%by weight of active agent. Application forms of formulation may forexample contain from 0.01 to 20% by weight, preferably from 0.01 to 5%by weight of active agent. Whereas commercial products will preferablybe formulated as concentrates, the end user will normally employ diluteformulations.

[0096] The Examples which follow serve to illustrate the invention,“active ingredient” denoting a mixture of compound I and a compound ofcomponent b) in a specific mixing ratio. Formulation Examples Wettablepowders a) b) c) active ingredient [comp a:comp b) = 25% 50% 75% 1:3(a),1:2(b), 1:1(c)] sodium lignosulfonate  5%  5% — sodium lauryl sulfate 3% —  5% sodium diisobutylnaphthalenesulfonate —  6% 10% phenolpolyethylene glycol ether —  2% — (7-8 mol of ethylene oxide) highlydispersed silicic acid  5% 10% 10% kaolin 62% 27% —

[0097] The active ingredient is thoroughly mixed with the adjuvants andthe mixture is thoroughly ground in a suitable mill, affording wettablepowders which can be diluted with water to give suspensions of thedesired concentration. Emulsifiable concentrate active ingredient (compa:comp b) = 1:6) 10% octylphenol polyethylene glycol ether  3% (4-5 molof ethylene oxide) calcium dodecylbenzenesulfonate  3% castor oilpolyglycol ether (35 mol of ethylene oxide)  4% cyclohexanone 30% xylenemixture 50%

[0098] Emulsions of any required dilution, which can be used in plantprotection, can be obtained from this concentrate by dilution withwater. Dusts a) b) c) active ingredient [comp a:comp b) = 1:6(a),  5% 6%  4% 1:2(b), 1:10(c)] talcum 95% — — kaolin — 94% — mineral filler —— 96%

[0099] Ready-for-use dusts are obtained by mixing the active ingredientwith the carrier and grinding the mixture in a suitable mill. Suchpowders can also be used for dry dressings for seed. Extruder granulesactive ingredient (comp a:comp b) = 2:1) 15% sodium lignosulfonate  2%carboxymethylcellulose  1% kaolin 82%

[0100] The active ingredient is mixed and ground with the adjuvants, andthe mixture is moistened with water. The mixture is extruded and thendried in a stream of air. Coated granules active ingredient (comp a:compb) = 1:10)  8% polyethylene glycol (mol. wt. 200)  3% kaolin 89%

[0101] The finely ground active ingredient is uniformly applied, in amixer, to the kaolin moistened with polyethylene glycol. Non-dustycoated granules are obtained in this manner. Suspension concentrateactive ingredient (comp a:comp b) = 1:8) 40% propylene glycol 10%nonylphenol polyethylene glycol ether  6% (15 mol of ethylene oxide)sodium lignosulfonate 10% carboxymethylcellulose  1% silicone oil (inthe form of a 75% emulsion in water)  1% water 32%

[0102] The finely ground active ingredient is intimately mixed with theadjuvants, giving a suspension concentrate from which suspensions of anydesired dilution can be obtained by dilution with water. Using suchdilutions, living plants as well as plant propagation material can betreated and protected against infestation by microorganisms, byspraying, pouring or immersion.

[0103] Slow Release Capsule Suspension

[0104] 28 parts of a combination of the compound of formula I (componenta) and a compound of component b), or of each of these compoundsseparately, are mixed with 2 parts of an aromatic solvent and 7 parts oftoluene diisocyanate/polymethylene-polyphenylisocyanate-mixture (8:1).This mixture is emulsified in a mixture of 1.2 parts ofpolyvinylalcohol, 0.05 parts of a defoamer and 51.6 parts of water untilthe desired particle size is achieved. To this emulsion a mixture of 2.8parts 1,6-diaminohexane in 5.3 parts of water is added. The mixture isagitated until the polymerization reaction is completed.

[0105] The obtained capsule suspension is stabilized by adding 0.25parts of a thickener and 3 parts of a dispersing agent. The capsulesuspension formulation contains 28% of the active ingredients. Themedium capsule diameter is 8-15 microns.

[0106] The resulting formulation is applied to seeds as an aqueoussuspension in an apparatus suitable for that purpose.

[0107] Biological Examples

[0108] A synergistic effect exists whenever the action of an activeingredient combination is greater than the sum of the actions of theindividual components.

[0109] The action to be expected E for a given active ingredientcombination obeys the so-called COLBY formula and can be calculated asfollows (COLBY, S. R. “Calculating synergistic and antagonisticresponses of herbicide combination”. Weeds, Vol. 15, pages 20-22; 1967):

[0110] ppm=milligrams of active ingredient (=a.i.) per liter of spraymixture

[0111] X=% action by active ingredient I using p ppm of activeingredient

[0112] Y=% action by active ingredient II using q ppm of activeingredient.

[0113] According to COLBY, the expected (additive) action of activeingredients I+II using p+q ppm of active ingredient is$E = {X + Y - \frac{X \cdot Y}{100}}$

[0114] If the action actually observed (O) is greater than the expectedaction (E), then the action of the combination is superadditive, i.e.there is a synergistic effect.

[0115] Alternatively the synergistic action may also be determined fromthe dose response curves according to the so-called WADLEY method. Withthis method the efficacy of the a.i. is determined by comparing thedegree of fungal attack on treated plants with that on untreated,similarly inoculated and incubated check plants. Each a.i. is tested at4 to 5 concentrations. The dose response curves are used to establishthe EC90 (i.e. concentration of a.i. providing 90% disease control) ofthe single compounds as well as of the combinations (EC 90_(observed)).The thus experimentally found values of the mixtures at a given weightratio are compared with the values that would have been found were onlya complementary efficacy of the components was present (EC 90(A+B)_(expected)). The EC 90 (A+B)_(expected) is calculated according toWadley (Levi et al., EPPO-Bulletin 16, 1986, 651-657):${{EC}\quad 90\left( {A + B} \right)_{expected}} = \frac{a + b}{\frac{a}{{{EC90}(A)}_{observed}} + \frac{b}{{{EC90}(B)}_{observed}}}$

[0116] wherein a and b are the weight ratios of the compounds A and B inthe mixture and the indexes (A), (B), (A+B) refer to the observed EC 90values of the compounds A, B or the given combination A+B thereof. Theratio EC90 (A+B)_(expected)/EC90 (A+B)_(observed) expresses the factorof interaction (F). In case of synergism, F is >1.

EXAMPLE B-1

[0117] Efficacy against Erysiphe graminis f.sp. tritici on Wheat

[0118] a) Protective Treatment:

[0119] Fifteen wheat seeds c.v. “Arina” are sown in plastic pots of 50ml and grown for 7 to 12 days at 22/19° C., 50-70% rH in the greenhouse.When the primary leaves have fully expanded, the plants are spraytreated with aqueous spray liquids containing the single compounds, ormixtures thereof (hereinafter a.i.). All compounds are used asexperimental or commercially available formulations, combinations areapplied as tank mixtures. The application comprises foliar spraying tonear runoff (three pots per treatment). 7 days after the application,the plants are inoculated in a settling tower with fresh spores ofErysiphe graminis f.sp. tritici by dusting the conidia on the testplants The plants are then incubated in a growth chamber at 20° C., 60%rH. Six days after inoculation, the percentage of infection on primaryleaves is evaluated. The efficacy of the a.i. is determined by comparingthe degree of fungal attack on treated plants with that on untreated,similarly inoculated and incubated check plants. Each a.i. is tested at3 to 5 concentrations. The results are evaluated according to the COLBYmethod.

[0120] b) Curative Treatment:

[0121] Wheat plants cv. Arina are grown in standard soil in 50 ml pots(approx. 15 plants per pot) in the greenhouse at 22/19° C. and 14 hourslight per day. At test begin the plants are 8 days old. For inoculation,conidia are dusted over the test plants and the plants are incubated at18-20° C. until treatment. The fungicide treatment is carried out 3 daysafter inoculation by spraying the test plants with diluted spraysuspensions of the individual active ingredients or mixtures, beingprepared by suspension in demineralized water and appropriate dilution.12 plants in 3 pots are used for each treatment. 3 to 4 days aftertreatment the tests are evaluated by estimating the percentage of fungalattack on the leaves. The activity is calculated relative to the diseaseon the check plants. The fungicide interactions in the mixtures arecalculated according to the COLBY method.

EXAMPLE B-2

[0122] Activity Against Uncinula Necator

[0123] Grape plants in the 4-6 leaf stage, variety Gutedel, areinoculated with conidia of Uncinula necator by dusting the conidia overthe test plants. After 2 days under high humidity and reduced lightintensity, the plants are incubated for 10-14 days in a growth chamberat 70% rH and 22° C. 3 days after inoculation the active ingredients andthe mixtures are applied by spraying aqueous suspensions being preparedby suspending the a.i.s in demineralized water and appropriate dilution.5 plants are used for every treatment. 12 days after inoculation thetests are evaluated by estimating the percentage of fungal leaf attackrelative to the disease on the check plants. The fungicide interactionsin the mixtures are calculated according to COLBY method.

[0124] The mixtures according to the invention exhibit good activity inthe methods of the above Biological Examples 1 and 2.

What is claimed is:
 1. A method of combating phytopathogenic diseases oncrop plants which comprises applying to the crop plants or the locusthereof being infested with said phytopathogenic disease an effectiveamount of a combination of a) a benzophenone of formula I

wherein R₁ is methoxy, methyl, hydroxy, acetoxy or pivaloyloxy, R₂ isC₁-C₄alkoxy or 2-halogenbenzyloxy, R₃ is C₁-C₄alkoxy, R₄ is C₁-C₄alkyl,halogen or trifluoromethyl, and R₅ is hydrogen, halogen, C₁-C₄alkoxy,trifluoromethyl or nitro; in association with b) the strobilurin offormula II


2. A method according to claim 1 wherein the applied amounts of thecomponents a) and b) are so selected as to enhance the fungicidalactivity of each other in a synergistic manner.
 3. A method according toclaims 1 or 2 wherein component a) is selected from the group comprising5-bromo-6,6′-dimethyl-2,2′,3′,4′-tetramethoxy-benzophenone,6-chloro-6′-methyl-2,2′,3′,4′-tetramethoxy-benzophenone,6-trifluoromethyl-6′-methyl-2,2′,3′,4′-tetramethoxy-benzophenone,6,6′-dimethyl-2,2′,3′,4′-tetramethoxy-benzophenone,5-bromo-6-chloro-6′-methyl-2,2′,3′,4′-tetramethoxy-benzophenone,6-chloro-5,6′-dimethyl-2,2′,3′,4′-tetramethoxy-benzophenone,5-chloro-2,6,6′-trimethyl-2′,3′,4′-trimethoxy-benzophenone,5-bromo-2,6,6′-trimethyl-2′,3′,4′-trimethoxy-benzophenone,5-nitro-2,6,6′-trimethyl-2′,3′,4′-trimethoxy-benzophenone,2,6,6′-trimethyl-5,2′,3′,4′-tetramethoxy-benzophenone,5-bromo-6,6′-dimethyl-2-hydroxy-2′,3′,4′-trimethoxy-benzophenone,5-bromo-6,6′-dimethyl-2-acetoxy-2′,3′,4′-trimethoxy-benzophenone, and5-chloro-6,6′-dimethyl-2-hydroxy-2′,3′,4′-trimethoxy-benzophenone.
 4. Afungicidal composition comprising a fungicidally effective combinationof components a) and b) according to claim 1 together with anagriculturally acceptable carrier, and optionally a surfactant.
 5. Acomposition according to claim 4 wherein the ratio of components a) andb) are so selected that the fungicidal activity is synergisticallyenhanced.
 6. A composition according to claims 4 or 5 wherein the weightratio of a) to b) is between 200:1 and 1:40.